The invention relates to a manual control apparatus, such as a control pedal for drive-by-wire control systems, and similar applications.
Manual control apparatuses, such as throttle control pedals for drive-by-wirethrottle control systems, are known in the art. Due to the fact that such pedals eliminate the mechanical linkage to the carburetor on an engine, hysteresis is often added to replicate the xe2x80x9cfeelxe2x80x9d of a pedal having a mechanical linkage. In particular, it is desirable for a rotatable member, for example a pedal, to generate an increased resistance during depression, and an ability stay at a fixed position with reduced force in order to avoid operator fatigue. This is typically provided by introducing a deliberate amount of frictional resistance to movement at one or more locations in the pedal mechanism. A similar effect may also be desirable in other manual control apparatuses such as a hand operated throttle, or a brake control pedal for a drive-by-wire control system, without limitation.
Although manual control apparatuses having hysteresis are known in the art, a desirable apparatus would have more precisely controlled hysteresis than is presently available. In addition, a desirable apparatus would also be light in weight, simple in manufacture, and simple in assembly with as few components as possible.
In addition to hysteresis, manual control apparatuses typically have a rotation sensor that indicates rotation of the rotatable member, for example a pedal, relative to a fixed point, such as a base to which the pedal is mounted. Precise registration of the rotatable member relative to the fixed point at a particular angle is important for both calibration, and for repeatability from apparatus to apparatus. In a throttle control pedal, the angle of rotation of the pedal is typically measured from the idle position. However, tolerance stack-up can cause a significant variation within a group of apparatuses. Tolerance stack-upand manufacturing variation may also cause significant variation within the rotation sensor. Therefore, a desirable apparatus would provide reduced variation in the rotation sensor system.
According to an aspect of the invention, a manual control apparatus is provided with a spring that biases a rotatable member relative to a base, and the body of the spring is forced against a friction element. The friction element rides upon a curved friction surface and is directly coupled to the rotatable member.
According to a further aspect of the invention, a manual control apparatus is provided having an angular position sensor with a housing and a pivot mounted to the housing. A rotatable member is coupled to the pivot and the angular position sensor indicates an angular position of the rotatable member. A stop pin is mounted on the housing and the rotatable member rests on the stop pin when in the idle position.
According to a still further aspect of the invention, a manual control apparatus is provided having an angular position sensor comprising a housing mounted to a base. The housing is coupled to a pivot to sense rotation thereof. The housing comprises a first abutment that defines a first datum plane perpendicular to an axis of rotation of the pivot, and a second abutment that defines a second datum plane perpendicular to the axis of rotation. A rotor within the housing is coupled to the pivot shaft, and a sensing element cooperates with the rotor to indicate an angular position thereof relative to the base. The sensing element rests upon the first abutment, and a rotor spring biases the rotor against the second abutment.
According to a still further aspect of the invention, a manual control apparatus is provided, comprising an angular position sensor comprising a housing coupled to a pivot to sense rotation thereof. The housing comprises a pair of opposing bosses that are received within recesses in a base. An idle stop is mounted to the housing and the base thereby retaining the bosses within the recesses. The housing is restrained within the base using the idle stop as a single fastener.
A method is also provided for applying hysteresis to a manual control apparatus by rotating a rotatable member in unison with a friction shoe resting on a curved friction surface, the friction shoe being directly coupled to the rotatable member, thereby generating frictional resistance between the friction shoe and friction surface.
The manual control apparatus of the invention is particularly well suited for use with a drive-by-wire system wherein a direct mechanical linkage to an engine throttle or brake hydraulic system, for example, is eliminated.